Conventionally known is a power demand control device by which, when the power usage of a plurality of devices has exceeded the contracted power amount, the power supply is shut down starting from the device higher in demand process priority order as a shutdown priority order, to execute a demand process. Japanese Patent Laying-Open No. 09-252533 (PTL 1) discloses a device as the above-mentioned power demand control device. This device sets a device address and a demand process priority order by the same and individual switch means for each device. Then, when the power usage exceeds the contracted power amount, the device individually shuts down the power of the devices in descending priority order in accordance with the demand process priority order set by the switch means before shutting down all of the plurality of devices by the entire breaker.